The present invention relates to hermetic refrigeration compressors and to the flow of suction gas into the shells thereof. With more particularity, the present invention relates to refrigeration compressors of the reciprocating type in which the flow of suction gas to the compression mechanism within the shell of the compressor is to and through a motor end cap and suction tube. With still more particularity, the present invention relates to an improved motor end cap/suction tube arrangement by which the flow of suction gas into and through the shell of a hermetic refrigeration compressor is managed so as to prevent the carrying of debris into the compression apparatus and to enhance the cooling of the motor by which the compression apparatus is driven.
Hermetic refrigeration compressors are compressors in which a motor-compressor combination is mounted internal of a hermetic shell. Such compressors are used in refrigeration systems such as air conditioners, heat pumps and the like for purposes of compressing refrigerant gas from a lower (suction) pressure to a higher (discharge) pressure.
Certain of such compressors are so-called low-side compressors meaning that the interior of the shell in which the motor-compressor is disposed contains refrigerant gas at suction pressure. Such gas surrounds the motor-compressor assembly and is drawn therefrom into the compression mechanism. The suction gas in a refrigeration compressor is a relatively low pressure gas which, even though relatively warm in terms of comparative refrigerant temperatures in other portions of the refrigeration system, is low enough to cool the still higher temperature motor portion of the motor-compressor by flow over, through and around it.
The use of motor end caps and suction tubes to channel the delivery of suction gas to the compression mechanism of a refrigeration compressor in a manner which cools the motor by which the compression apparatus is driven has long been known and there have been many improvements in such arrangements over the past decades. The use of motor end caps in such compressors, while advantageous, does bring certain disadvantages and difficulties that must be overcome in order to permit their use without adversely affecting suction gas flow or unnecessarily complicating compressor fabrication.
Among the disadvantages/difficulties that must be overcome when a motor end cap and suction tube arrangement is employed in a compressor is the need to minimize pressure drop in the suction gas flowing to the compression apparatus as a result of the use thereof. Further, the use of an end cap, which overlies the motor of the compressor, can potentially complicate the compressor assembly process which requires that a predetermined gap be set between the stator and rotor of the compressor drive motor once these components have been assembled into place during the compressor's manufacture. The setting of the rotor-stator gap requires access to the motor for that purpose and the use of a motor end cap, which is most often attached directly to and overlies the motor's stator, poses an obstacle to access to the rotor-stator gap. Difficulties in setting the rotor-stator gap can therefore be encountered to the extent that the end cap, in the process of its assembly to the motor-compressor, blocks access to and/or observation of the rotor-stator gap for gap setting purposes.
The need continues to exist for an improved motor end cap/suction tube arrangement in a refrigeration compressor which minimizes pressure drop in the flow of suction gas enroute to the compression mechanism, which prevents the entry of debris into or onto the compressor drive motor and compressor portions of the motor-compressor combination and which facilitates compressor manufacture and assembly by providing access to the rotor-stator gap so as to permit the setting of that gap conveniently and at minimal expense.